Method and device for measuring electric field distribution of semiconductor device

ABSTRACT

It comprises a voltage-application apparatus  2  for applying a predetermined voltage to a semiconductor device  1 , and holding it therein; a laser apparatus  3  for generating a laser beam  4  having a predetermined wavelength; an irradiation apparatus  5  for irradiating the laser beam  4  onto the two-dimensional circuit of the semiconductor device  1 , which is held in the applied state, so as to scan it two-dimensionally; an electromagnetic-wave detection/conversion apparatus  6  for detecting an electromagnetic wave, which is radiated from the laser-beam irradiation position, and converting the electromagnetic wave into an electric-field signal, which changes temporally; and phase-judgement means  71 , to which the temporally-changing electric-field signal output from the detection/conversion apparatus  6  is input, for judging the phase of the electric-field signal.

TECHNICAL FIELD

The present invention relates to a method and apparatus for measuringthe electric field distribution of semiconductor device, such assemiconductor elements and semiconductor integrated circuits, in anon-contact manner. Particularly, it relates to a method and apparatuswhich irradiates a laser beam in such a state that a voltage is appliedto a semiconductor device, and which measures an electric-fielddistribution from a radiated electromagnetic wave in a non-contactmanner. This electric-field measurement method and apparatus can beapplied to inspections for defective circuits, such as disconnection insemiconductor devices, defective doping, defective short-circuitsbetween layered films, and the like.

BACKGROUND ART

As a method for measuring the electric-field distribution insidesemiconductor device, such as semiconductor integrated circuits andsemiconductor elements, in a non-destructive/non-contact manner, aterahertz (THz) electromagnetic-wave imaging method using laser has beenknown (KIWA Toshihiko and TONOUCHI Masayoshi, “Back-scattered TerahertzImaging for Fault Isolation in Integrated Circuits,” Japan Society ofApplied Physics, Springtime Academic Lecture Meeting, ExtendedAbstracts, the Third Volume, p. 1,183, (Mar. 29, 2003)). This is one inwhich a THz electromagnetic wave is generated by irradiating a laserbeam onto a circuit surface after applying a voltage to the circuit of asemiconductor device and the electric-field strength at the laserirradiation position is measured from the amplitude intensity of thegenerated electromagnetic wave. However, since this conventional methodmakes use of the amplitude intensity of the generated electromagneticwave alone, the difference between the electric-field directions cannotbe distinguished and the obtained information is less so that it isinsufficient for the inspection or failure diagnosis for semiconductordevice. Moreover, the spatial resolution of measurement is prescribed bythe diffraction limit of irradiating laser beam, and accordingly thereis a problem in view of resolution in order to measure theelectric-field distribution of fine semiconductor integrated circuit.Further, the conventional method can measure the electric-fielddistribution of entire circuit only, and cannot measure theelectric-field distribution of specific region, such as the signalchannel alone, for instance.

Moreover, as a technique which is related to the aforementioned priorart, a technique (FIG. 1) has been known, technique in which anultra-short optical pulse is irradiated onto a semiconductor switch toradiate a terahertz electromagnetic wave into air (D. H. Auston and M.C. Nuss, “ELECTROOPTIC GENERATION AND DETECTION OF FEMTOSECONDELECTRICAL TRANSIENTS,” IEEE JOURNAL OF QUANTUM ELECTRONICS, Vol. 24,pp. 184-197, FEBRUARY 1988.). In FIG. 1, a low-temperature grown (LT)GaAs thin film, which works as a photoconduction film, is grown on asemi-insulative GaAs substrate, and further antenna structures, whichare disposed at intervals of 5 μm approximately, are made on it with agold alloy. In general, an LT-GaAs has been used as a photoconductingthin film in which an electric current flows in an instant only when anoptical pulse is irradiated. The gold-alloy portions double aselectrodes, and are connected with a direct-current voltage source. Thecentral projections act as a micro dipole antenna, and, when a pulselaser beam is emitted to this gap portion to excite it, the carrier isexcited from the valence band to the conduction band by means of lightabsorption, and the excited carrier relaxes after it is accelerated bythe applied voltage. When considering this movement of the carrier aninstant electric current, a pulse electromagnetic wave, which is inproportion to the time derivative of this electric current, generates.

As aforementioned, in the prior art, there are such problems that thedirection of electric field cannot be distinguished, the spatialresolution of electric-field distribution measurement is low, and theelectric-field distribution of specific region cannot be measured.

The present invention is one which has been created anew in order tosolve such problematic points. That is, the object of the presentinvention is to provide an electric-field distribution measurementmethod and apparatus, which can distinguish the direction of electricfield, whose spatial resolution is high, and which can measure theelectric field in specific region.

DISCLOSURE OF THE INVENTION

An electric-field distribution measurement method of the presentinvention for a semiconductor device comprises: a holding step ofapplying a predetermined voltage to a semiconductor device on which atwo-dimensional circuit is formed, and holding the semiconductor devicein an applied state; an irradiation step of irradiating a laser beamhaving a predetermined wavelength onto the two-dimensional circuit ofthe semiconductor device, which is held in the applied state, so as toscan it two-dimensionally; a detection/conversion step of detecting anelectromagnetic wave, which is radiated from a laser-beam irradiationposition, and converting it into an electric-field signal, which changestemporally; and a judgement step of judging the phase of theelectric-field signal which changes temporally.

Since the phase of the temporally changing waveform of theelectric-field signal of the electromagnetic wave, which is radiatedfrom the laser-beam irradiation position, is judged and the direction ofthe electric field at the laser-beam irradiation position is judgedusing the fact that the judged phase depends on the direction of theelectric field at the laser beam irradiation position, it is possible todistinguish the direction of the electric field.

In the aforementioned method, it can be adapted so that it furthercomprises a sampling step of sampling the amplitude of an electric fieldat a predetermined time in said electric-field signal, which changestemporally.

It becomes possible to measure an electric-field strength distributionas well using the fact that the amplitude of the electric field, whichis subjected to sampling in the sampling step, is proportional to thestrength of the electric field at said laser-beam irradiation position.

Moreover, it is advisable that the predetermined time of the samplingstep can comprise a plurality of times; and the sampling step can carryout sampling the amplitude of the electric field at the plurality oftimes, thereby measuring the electric-field strength distribution atdifferent times.

A time-series electric-field distribution at the identical laser-beamirradiation position can be obtained, and accordingly the identificationof doping locations on the substrate of the semiconductor device, andthe like, become possible. Further, since the radiated electromagneticwave is reflected by the interface whose refractive index changes in thedepth direction of the substrate so that the reflected wave is radiatedfrom the semiconductor device's surface retardingly, depth-directioninformation can be obtained by subjecting the amplitude of the electricfield of the reflected wave to sampling at different times.

It can be adapted so that the predetermined voltage of said holding stepcan comprise a voltage, which is modulated with a predeterminedfrequency; and said detection/conversion step can convert anelectromagnetic wave, which is modulated with the modulated frequency,into an electric-field signal, which changes temporally.

It becomes possible to measure the electric field of a circuit portionalone to which the modulated voltage is applied.

It is advisable as well that said laser beam can be adapted to be onewhich is modulated with a predetermined frequency.

It is possible to measure the electric field distribution of a portiononto which the laser beam is irradiated.

Said irradiation step can irradiate said laser beam onto saidtwo-dimensional circuit so as to scan it two-dimensionally by way of anear-field optical system.

It becomes possible to make the spatial resolution of the electric-fielddistribution measurement higher than the diffraction limit.

Said predetermined wavelength of said irradiation step can be adapted tobeing selected so that said laser beam is absorbed by the material ofsaid semiconductor device.

A large number of optical carriers are generated by the irradiated laserbeam so that the intensity of the radiated electromagnetic waveincreases, and accordingly the S/N of the detection/conversion stepimproves.

Moreover, an electric-field distribution measurement apparatus of thepresent invention for solving said assignment is characterized in thatit comprises: a voltage-application apparatus for applying apredetermined voltage to a semiconductor device on which atwo-dimensional circuit is formed, and holding the semiconductor devicein an applied state; a laser apparatus for generating a laser beamhaving a predetermined wavelength; an irradiation apparatus forirradiating the laser beam onto the two-dimensional circuit of thesemiconductor device, which is held in the applied state, so as to scanit two-dimensionally; an electromagnetic-wave detection/conversionapparatus for detecting an electromagnetic wave, which is radiated fromthe laser-beam irradiation position, and converting the electromagneticwave into an electric-field signal, which changes temporally; andphase-judgement means, to which the temporally-changing electric-fieldsignal output from the detection/conversion apparatus is input, forjudging the phase of the electric-field signal, thereby measuring theelectric-field direction distribution using the fact that the phase,which is judged by the phase-judgement means, depends on theelectric-field direction at the laser-beam irradiation position.

In the aforementioned apparatus, it can be adapted so that it furthercomprises electric-field amplitude sampling means, to which saidtemporally-changing electric-signal output from the electromagnetic-wavedetection/conversion apparatus is input, for sampling the amplitude ofan electric field at a predetermined time in said electric-field signaland it measures an electric-field strength distribution of saidsemiconductor device as well using the fact that the amplitude of theelectric field, which is subjected to sampling by the sampling means, isproportional to the strength of the electric filed at the laser-beamirradiation position.

Moreover, in the electric-field distribution measurement apparatus ofthe present invention for a semiconductor device, said electric-fieldamplitude sampling means can carry out sampling the amplitude of theelectric field at a plurality of predetermined times, and can therebymeasure the electric-field strength distribution at different times.

Further, said voltage-application apparatus can apply a voltage, whichis modulated with a predetermined frequency, to said semiconductordevice; and said electromagnetic-wave detection/conversion apparatus canconvert an electromagnetic wave alone, which is modulated with themodulated frequency, into an electric-field signal, which changestemporally, and thereby the electric-field distribution of a circuitportion, to which the modulated voltage is applied, can be measured.

It can be adapted so that it comprises modulation means for modulatingsaid laser beam with a predetermined frequency.

In the electric-field distribution measurement apparatus of the presentinvention for a semiconductor device, said irradiation device cancomprise a near-field optical system, and can thereby irradiate saidlaser beam onto said two-dimensional circuit so as to scan ittwo-dimensionally by way of the near-field optical system.

Moreover, said laser apparatus can generate a laser beam with awavelength which is absorbed by the material of said semiconductordevice.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a principle diagram on the background art in which anultra-short optical pulse is irradiated onto a semiconductor switch toradiate a terahertz electromagnetic wave into air.

FIG. 2 is not only an outline diagram of an electric-field distributionmeasurement apparatus of the present invention for a semiconductordevice, but also is an outline diagram of an electric-field distributionmeasurement apparatus A of Example No. 1 for a semiconductor device.

FIG. 3 is a diagram for explaining the electric-field signal of anelectromagnetic wave, which is radiated from a semiconductor device, andthe sampling time.

FIG. 4 is a color image for showing an electric-field distributionmeasurement result of Example No. 1.

FIG. 5 is an outline diagram of an electric-field distributionmeasurement apparatus B of Example No. 2 for a semiconductor device.

FIG. 6 is an enlarged diagram of the leading end of a near-field opticalprobe 54 of the electric-field distribution measurement apparatus B ofExample No. 2 for a semiconductor device.

FIG. 7 is a color image for showing an electric-field distributionmeasurement result of Example No. 2.

FIG. 8 is a color image for showing an electric-field distributionmeasurement result of Example No. 3.

FIG. 9 is a color image for showing an electric-field distributionmeasurement result of Example No. 4.

FIG. 10 is a color image for showing an electric-field distributionmeasurement result of Example No. 5.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferable embodiment modes of the present invention will be hereinafterdescribed with reference to the drawings. Note that, in the respectivediagrams, common parts are designated with identical symbols in order toabbreviate duplicate descriptions.

FIG. 2 is an outline diagram of an electric-field distributionmeasurement apparatus A of Example No. 1 for a semiconductor device,outline diagram which shows an embodiment mode of the present invention.As shown in this diagram, the electric-field distribution measurementapparatus A is equipped with a voltage-application apparatus 2, a laserapparatus 3, an irradiation apparatus 5, an electromagnetic-wavedetection/conversion apparatus 6, and phase judgement means 71.

The voltage-application apparatus 2 is an electric power circuit,applies a predetermined voltage to the two-dimensional circuit of asemiconductor 1, a measuring object, and holds it in an applied state.“Applying a predetermined voltage to something and holding it in anapplied state” refers to applying a voltage (DC±16 V, for example),which is suitable for the semiconductor device 1, to theelectric-power-source line and holding the earth line in a groundedstate. Therefore, in this applied state, the circuit portion of thesemiconductor device 1, which is connected with theelectric-power-source line, becomes a predetermined voltage, and thecircuit portion, which is connected with the earth line, becomes beinggrounded (0 volt, for instance), thereby generating a voltage differencebetween them. The electric-power-source application apparatus 2 candesirably be capable of supplying ±direct-current voltage and modulatedvoltage variably. Even when the semiconductor device 1, a measuringobject, changes, it is possible to apply a voltage, which is suitablefor it. Moreover, it is possible to apply a voltage, which is modulatedwith a predetermined frequency, to the signal line of the semiconductordevice 1, for example.

The laser apparatus 3 generates a laser beam 4. As for the laserapparatus 3, it is possible to use mode-locked laser or fiber laser, andthe like, which generates the laser beam 4 of ultra-short optical pulsewhose pulse width is femtoseconds, for instance. As for the laserapparatus 3, as far as it is one in which an electromagnetic wave isgenerated when irradiating the generated laser beam 4 onto thesemiconductor device 1, the laser beam 4 is not needed to be anultra-short optical pulse in particular, it can be twocw-oscillation-semiconductor-laser units, which generate cw laser beamswhose oscillation wavelengths are close to each other, for example. Thewavelength of the laser beam 4 can desirably be a wavelength which isabsorbed by the substrate material of the semiconductor device 1, and itis advisable to select it depending on the substrate material ofsemiconductor device. That is, when the substrate material is Si, it isdesirable to use a laser apparatus, which generates a laser beam whosewavelength is 1,117 nm or less; when it is GaAs, it is desirable to usea laser apparatus, which generates a laser beam whose wavelength is 885nm or less; and when it is Ge, it is desirable to use a laser apparatus,which generates a laser beam whose wavelength is 1,879 nm or less,respectively. As for the laser apparatus, which generates a laser beamwhose wavelength is absorbed by the substrate material of semiconductordevice, fiber laser, in which fibers doped with Yb or Er ions areadapted to the amplification medium, is suitable. Further, thewavelength of the laser beam 4 can be a wavelength, which transmitsthrough the package of the semiconductor device 1 and is absorbed by thesubstrate material of the semiconductor device. It becomes unnecessaryto remove the package. Moreover, the mode of the laser beam 4 canpreferably be a single mode. The single mode is such that the beamquality is high and it is possible to irradiate it onto thesemiconductor device 1 while condensing it to the diffraction limit.Note that, when constituting the package of a material through which thelaser beam 4 transmits, it becomes unnecessary to select a wavelengthwhich transmits through the package.

The irradiation apparatus 5 irradiates the laser beam 4 onto thetwo-dimensional circuit of the semiconductor device 1 so as to scan ittwo-dimensionally. In the electric-field distribution measurementapparatus A of FIG. 2, the irradiation apparatus 5 comprises a beamsplitter 51, which splits the laser beam 4 into two beams, a condenserlens 52, which condenses one of the split laser beams (exciter beam 41)and irradiates it to the semiconductor device 1, and an x-y movementstage 53, on which the semiconductor device 1 is placed and which movesit in the x-direction (direction crossing perpendicularly with the pageplane) and in the y-direction (page plane direction), and thesemiconductor device 1, which is placed on the stage 53, undergoes thex-y movement by the movement of the x-y movement stage 53, the condensedirradiation spot of the exciter beam 41 by means of the condenser lens52 scans on the two-dimensional circuit of the semiconductor device 1.By inserting a mirror behind the beam splitter 51, it is possible toadapt so that the exciter beam 41, which is split by the splitter 51, iscondensed and irradiated from the rear surface of the semiconductordevice 1. By thus doing, since the irradiated exciter beam 41 is notreflected at the metallic films, and the like, which constitute thecircuit, it is possible to detect radiated electromagnetic waveefficiently. Moreover, by inserting a near-field optical probe behindthe condenser lens 52, it is advisable to adapt the irradiationapparatus 5 to irradiate evernescent wave, which leaks out from theprobe's leading end, to the semiconductor device 1. It is possible tominimize the irradiation spot close to the diameter of the probe'sleading end, and accordingly it is possible to enhance the spatialresolution of electric-field distribution measurement greater than thediffraction limit of light. Note that, by inserting a galvanometermirror, for example, behind the condenser lens 52, it is advisable toadapt the irradiation apparatus 5 to irradiate the exciter beam 41,which is split by the beam splitter 51, to the stationary semiconductordevice 1 on the stage so as to scan it two-dimensionally.

The electromagnetic-wave detection/conversion apparatus 6 comprises anoff-axis parabolic mirror 61, in which a hole through which theirradiated laser beam passes is opened, an off-axis parabolic mirror61′, which is free of hole, an electromagnetic-wave detector 62, and alock-in amplifier 63. The off-axis parabolic mirrors 61, 61′ constitutea condenser optical system, and let electromagnetic wave, which isradiated from the semiconductor device 1, enter the detector 62efficiently. For the electromagnetic-wave detector 62, it is possible touse photoconductive antennas, or electro-optical crystals, such as ZnTe.To the electromagnetic-wave detector 62, the other beam (trigger beam42), which is split by the beam splitter 51, enters while being retardedby a retardation line, which is constituted of a corner cube 9 and amirror 10, and the detector 62 is gated by the trigger beam. It isadvisable to install an optical filter, which transmits electromagneticwave alone, to the electromagnetic-wave detector 62. It is possible toraise the S/N by cutting the background light, such as laser beam, whichis reflected at the metallic films of the semiconductor device 1, andthe like. When the radiated electromagnetic wave is modulated, it ispossible to raise the S/N by synchronizing the lock-in amplifier 63 withthe modulated frequency; and at the same, in the case of applying themodulated voltage to the signal line with the voltage-applicationapparatus 2 as aforementioned, it is possible to convert theelectromagnetic wave, which is radiated from the signal line, alone.

The phase judgement means 71 is subjected to the input oftemporally-changing signal of the electric field of the electromagneticwave, temporally-changing signal which is output from thedetection/conversion apparatus 6, and judges the phase of thetemporally-changing signal. FIG. 3 is one which shows temporal changesof the electric-field amplitude of the electromagnetic waveschematically, and it is judged to be the normal phase in the case ofthe continuous line and to be the reverse phase in the case of thedotted line. In the electric-field distribution measurement apparatus A,since a personal computer 7 carries out the function, the personalcomputer 7 comes to have the built-in phase judgement means 71. Thepersonal computer 7 controls the laser apparatus 3 and x-y movementstage 53, judges whether the phase of the temporally-changing signal ofthe electric field of the electromagnetic wave, temporally-changingsignal which is input from the electromagnetic-wave detection/conversionapparatus 6, is the normal phase or reverse phase, and displays thejudgement results at positions, which correspond to the semiconductordevice 1, on a CRT 73 according to colors.

It is advisable to let the personal computer 7 have the function ofelectromagnetic-field amplitude sampling means. Theelectromagnetic-field amplitude sampling means carries out sampling theamplitude of the electric field at predetermined times (τ₀, τ₁ of FIG.3, for instance) in the temporally-changing signal of the electric fieldof the electromagnetic wave, the temporally-changing signal which isinput from the electromagnetic-wave detection/conversion apparatus 6.The personal computer 7 carries out sampling the amplitude of theelectric field at predetermined times in the temporally-changing signalof the electric field of the electromagnetic wave, temporally-changingsignal which is input from the electromagnetic-wave detection/conversionapparatus 6, and displays the sampling results at positions, whichcorrespond to the semiconductor device 1, on the CRT 73 according to thecolors' shading.

In accordance with an electric-field distribution measurement method ofthe present invention using the above-described electric-fielddistribution measurement apparatus A, it comprises: a holding step ofholding the semiconductor device 1 in a predetermined voltageapplication state; an irradiation step of irradiating the laser beam 4onto the two-dimensional circuit of the semiconductor device 1 so as toscan it two-dimensionally; a detection/conversion step of detecting anelectromagnetic wave, which is radiated from the irradiation position,and converting it into an electric-field signal, which changestemporally; and a phase judgement step of judging the phase of theelectric-field signal, thereby measuring the direction of the electricfield at the irradiation position from the phase of the electric field.

In accordance with an electric-field distribution measurement method ofthe present invention using the modified mode of the above-describedelectric-field distribution measurement apparatus A, it furthercomprises a sampling step of sampling the amplitude of an electric fieldat a predetermined time in the electric-field signal, thereby measuringan electric-field strength at the irradiation position as well from theamplitude of the electric field.

Moreover, by applying a voltage, which is modulated with a predeterminedfrequency, to the signal line of the semiconductor device 1, forexample, with the voltage-application apparatus 2, and by detecting theelectromagnetic wave of the modulated frequency alone with theelectromagnetic-wave detection/conversion apparatus 6, it is possible tomeasure an electric-field distribution of the signal line alone, forinstance.

Further, by using a near-field optical probe for the irradiationapparatus 5, it is possible to enhance the spatial resolution ofelectric-field measurement to the diffraction limit of the laser beam 4or more.

By letting the personal computer 7 have a phase judgement step and anelectric-field amplitude sampling step of sampling the amplitude of anelectric field at a plurality of times, it is possible to measure atime-series electric-field direction at an identical position in thesemiconductor device 1, and an electric-field strength thereat.

EXAMPLE NO. 1

Above-described FIG. 2 is a constitutional example of an electric-fielddistribution measurement apparatus A of Example No. 1 of the presentinvention. That is, it was one in which, by irradiating the laser beam 4onto the semiconductor device 1 which was in the voltage applicationstate, an electromagnetic wave was generated from the irradiationposition; and the radiated electromagnetic wave was detected by theelectromagnetic-wave detection/conversion apparatus 6, thereby measuringthe phase of the temporally-changing signal of the electric field of theelectromagnetic wave.

The semiconductor device 1 was a test sample on which the test patternshown in (a) of FIG. 4 was formed. This sample was one in which goldwires of 30 μm width were formed by separating them at intervals of 25μm on an InP substrate. It was adapted so that +2 V and −2 V directcurrents were applied alternately to the gold wires from thevoltage-application apparatus 2.

For the laser apparatus 3, mode-locking titanium-sapphire laser wasused. From this laser apparatus 3, the laser beam 4, whose wavelengthwas 790 nm, pulse width was 100 fs, pulse repetition was 82 MHz andaverage power was 36 mW, was radiated.

The focal length of the condenser lens 52 of the irradiation apparatus 5was 100 mm, and the irradiation spot diameter of the exciter beam 41 onthe test sample 1 was 25 μm.

The laser beam 4 was adapted so that it was modulated to an about 1-KHzfrequency and was irradiated to the test sample 1.

As the electromagnetic-wave detector 62 of the electromagnetic-wavedetection/conversion apparatus 6, a photoconductive antenna was used.

(b) of FIG. 4 is the result of measuring the phase by irradiating theexciter laser beam 41 onto the test sample 1 while holding it in thevoltage application state, and is displayed in colors; in red at theposition from which the electromagnetic wave with the normal phase(corresponding to the continuous line of FIG. 3) was radiated; in blueat the positions from which the electromagnetic wave with the reversephase (corresponding to the dotted line of FIG. 3) was radiated; and inblack at the positions from which no electromagnetic wave was radiated.From (a) and (b) of FIG. 4, a leftward electric field was applied to thered region and a rightward electric field was applied to the blueregions, and accordingly it is understood that it was possible tomeasure the electric-field direction with the electric-fielddistribution measurement apparatus A of present Example No. 1.

(c) of FIG. 4 is the result of measuring the phase without applying avoltage to the test sample 1, and the entire surface was displayed inone color, black, because there was no electric field so that noelectromagnetic wave was radiated.

EXAMPLE NO. 2

FIG. 5 is a constitutional example of an electric-field distributionmeasurement apparatus B of Example No. 2 of the present invention.Except that the irradiation apparatus 5 comprised a near-field opticalprobe 54, and that the personal computer 7 comprised sampling means 72for sampling the electric-field amplitude of a temporally-changingsignal of an electric field of an electromagnetic wave at apredetermined time, it was the same as Example No. 1.

FIG. 6 is an enlarged diagram of the leading-end portion of the probe54, which is surrounded with the circle of FIG. 5. The probe 54 was madeof a transparent medium in which the exciter laser beam 41 transmitted,and was covered with a metallic film 542 other than the entrance end andemission end. The diameter of the emission end's opening portion, whichwas not covered with the metallic film 542, was 0.2 μm; and anevernescent wave 41′ of the exciter beam 41 leaked out through thisopening portion, and was irradiated onto the semiconductor device 1.

The semiconductor device 1 of Example No. 2 was a test sample likeExample No. 1 as well, and had dimensions shown in FIG. 7. That is, thewidth of a gold wire was 6 μm, and the interval between a gold wire anda gold wire was 1 μm.

(b) of FIG. 7 is the result of measuring the phase and the amplitude ofelectric field by irradiating the evernescent wave 41′ of the exciterlaser beam 41 onto the test sample 1 while holding it in the voltageapplication state, and the phase is distinguished in red and blue and atthe same time the magnitude of the amplitude is displayed in theconcentration of colors. From this, it is understood that theelectric-field direction and electric-field strength were measured evenwhen the intervals between the gold wires were 1 μm. That is, byirradiating the exciter beam 41 via the near-field optical prove 54,1-μm spatial resolution was achieved.

EXAMPLE NO. 3

FIG. 8 is the result of measuring an electric-field distribution, usingan operational amplifier (LM301AH: National Semiconductor) as thesemiconductor device 1 of the electric-field measurement apparatus A ofExample No. 1 of the present invention. FIG. 8 (a) is the result ofmeasuring the electric-field distribution in such a state that the laserbeam 4, which was modulated by modulating the laser apparatus 3 with2-KHz frequency, was generated and ±16 V (direct current) was suppliedto the power-source line of the operational amplifier 1 and −10 V(direct current) was supplied to the signal line thereof with thevoltage application apparatus 2, respectively, and it was possible toknow the entire electric-field distribution of the operational amplifier1. FIG. 8 (b) is the result of measuring the electric-field distributionin such a state that ±10 V modulated voltage, which was modulated with 2KHz, was supplied to the signal line of the operational amplifier 1 withthe voltage-application apparatus 2, instead of modulating the laserapparatus 3, and it was possible to know the electric-field distributionof the signal line alone.

EXAMPLE NO. 4

FIG. 9 is the result of measuring the electric-field distribution of theoperational amplifier 1, which was used in Example No. 3, with highresolution, using the electric-field measurement apparatus B of ExampleNo. 2. That is, the upper left-side diagram is the result of measuringthe electric-field distribution in such a state that the laser beam 4,which was modulated by modulating the laser apparatus 3 with 2-KHzfrequency, was generated and ±16 V (direct current) was supplied to thepower-source line of the operational amplifier 1 and −10 V (directcurrent) was supplied to the signal line thereof with the voltageapplication apparatus 2, respectively. Meanwhile, the upper right-sidediagram of FIG. 9 is the result of measuring the electric-fielddistribution after part of the circuit was disconnected intentionally asshown in the right bottom, and it is understood that the electric-fielddistribution was changed greatly by the disconnection and it is shownthat the present invention could be applied to the inspection for thedisconnection of semiconductor device, and the like.

EXAMPLE NO. 5

FIG. 10 is the result of measuring the electric-field distribution ofthe operational amplifier 1 of Example No. 3 for the temporal change ofthe electric-field distribution in a specific area of the operationalamplifier 1, using the electric-field measurement apparatus B of ExampleNo. 2. The left diagram of FIG. 10 is the electric-field distribution ata time (τ=0 ps) when the amplitude of the electric field first becamethe peak value; the central diagram is that at τ=5 ps; and the rightdiagram is the electric-field distribution at τ=9.5 ps. Although theoperational amplifier 1's the voltage applying/holding state by thevoltage-application apparatus 2 was constant, the electric-fielddistribution changed with time series, it is believed to result from thefact that it came under influence other than the optical carrier, whichwas generated by the irradiation of the exciter beam 41, the influenceof doping level's inhomogeneity, for instance. Therefore, it was shownthat it was possible to measure the temporal change of theelectric-filed distribution by sampling the amplitude of the electricfield at different times and accordingly it was possible to evaluate thedoping level's inhomogeneity, and so forth.

INDUSTRIAL APPLICABILITY

The electric-field distribution measurement method and apparatus of thepresent invention for a semiconductor can be utilized not only in theelectric-field distribution measurement at the development stages ofsemiconductor devices, but also can be utilized in the inspection forthe disconnection, defect, operational failure, and the like, at theproduct production stages of semiconductor devices.

1. An electric-field distribution measurement method for a semiconductordevice, comprising: a holding step of applying a predetermined voltageto a semiconductor device on which a two-dimensional circuit is formed,and holding the semiconductor device in an applied state; an irradiationstep of irradiating a laser beam having a predetermined wavelength ontothe two-dimensional circuit of the semiconductor device, which is heldin the applied state, so as to scan it two-dimensionally; adetection/conversion step of detecting an electromagnetic wave, which isradiated from a laser-beam irradiation position on said semiconductordevice to which said laser beam is irradiated, and converting theelectromagnetic wave into an electric-field signal, which changestemporally; and a judgement step of judging the phase of theelectric-field signal which changes temporally, and the electric-fielddistribution measurement method for the semiconductor device beingcharacterized in that the electric-field direction distribution of saidsemiconductor device is measured using the fact that the phase, which isjudged in said judgement step, depends on the electric-field directionat the laser-beam irradiation position.
 2. The electric-fielddistribution measurement method for a semiconductor device set forth inclaim 1 being characterized in that it further comprises a sampling stepof sampling the amplitude of an electric field at a predetermined timein said electric-field signal, which changes temporally, and anelectric-field strength distribution is measured as well using the factthat the amplitude of the electric field, which is subjected to samplingin the sampling step, is proportional to the strength of the electricfiled at said laser-beam irradiation position.
 3. The electric-fielddistribution measurement method for a semiconductor device set forth inclaim 2 being characterized in that the predetermined time of thesampling step comprises a plurality of times; and the sampling stepcarries out sampling the amplitude of the electric field at theplurality of times, thereby measuring the electric-field strengthdistribution at different times.
 4. The electric-field distributionmeasurement method for a semiconductor device set forth in claim 1,being characterized in that said laser beam is one which is modulatedwith a predetermined frequency.
 5. The electric-field distributionmeasurement method for a semiconductor device set forth in claim 1,being characterized in that the predetermined voltage of said holdingstep comprises a voltage, which is modulated with a predeterminedfrequency; and said detection/conversion step converts anelectromagnetic wave, which is modulated with the modulated frequency,into an electric-field signal, which changes temporally, therebymeasuring the electric-field distribution of a circuit portion to whichthe modulated voltage is applied.
 6. The electric-field distributionmeasurement method for a semiconductor device set forth in claim 1,being characterized in that said irradiation step irradiates said laserbeam onto said two-dimensional circuit so as to scan ittwo-dimensionally by way of a near-field optical system.
 7. Theelectric-field distribution measurement method for a semiconductordevice set forth in 1, being characterized in that said predeterminedwavelength of said irradiation step is selected so that said laser beamis absorbed by the material of said semiconductor device.
 8. Anelectric-field distribution measurement apparatus for a semiconductordevice, comprising: a voltage-application apparatus for applying apredetermined voltage to a semiconductor device on which atwo-dimensional circuit is formed, and holding the semiconductor devicein an applied state; a laser apparatus for generating a laser beamhaving a predetermined wavelength; an irradiation apparatus forirradiating the laser beam onto the two-dimensional circuit of thesemiconductor device, which is held in the applied state, so as to scanit two-dimensionally; an electromagnetic-wave detection/conversionapparatus for detecting an electromagnetic wave which is radiated from alaser-beam irradiation position on said semiconductor device to whichsaid laser beam is irradiated, and converting the electromagnetic waveinto an electric-field signal, which changes temporally; andphase-judgement means, to which the temporally-changing electric-fieldsignal output from the detection/conversion apparatus is input, forjudging the phase of the electric-field signal, and the electric-fielddistribution measurement apparatus for the semiconductor device beingcharacterized in that it measures the electric-field directiondistribution of said semiconductor device using the fact that the phase,which is judged by the phase-judgement means, depends on theelectric-field direction at the laser-beam irradiation position.
 9. Theelectric-field distribution measurement apparatus for a semiconductordevice set forth in claim 8 being characterized in that it furthercomprises electric-field amplitude sampling means, to which saidtemporally-changing electric-signal output from the electromagnetic-wavedetection/conversion apparatus is input, for sampling the amplitude ofan electric field at a predetermined time in said electric-field signaland it measures an electric-field strength distribution of saidsemiconductor device as well using the fact that the amplitude of theelectric field, which is subjected to sampling by the sampling means, isproportional to the strength of the electric filed at the laser-beamirradiation position.
 10. The electric-field distribution measurementapparatus for a semiconductor device set forth in claim 9 beingcharacterized in that said electric-field amplitude sampling meanscarries out sampling the amplitude of the electric field at a pluralityof predetermined times, and thereby measures the electric-field strengthdistribution at different times.
 11. The electric-field distributionmeasurement apparatus for a semiconductor device set forth in claim 8,being characterized in that it comprises modulation means for modulatingsaid laser beam with a predetermined frequency.
 12. The electric-fielddistribution measurement apparatus for a semiconductor device set forthin claim 8, being characterized in that said voltage-applicationapparatus applies a voltage, which is modulated with a predeterminedfrequency, to said semiconductor device; and said electromagnetic-wavedetection/conversion apparatus converts an electromagnetic wave alone,which is modulated with the modulated frequency, into an electric-fieldsignal, which changes temporally, and thereby measures theelectric-field distribution of a circuit portion to which the modulatedvoltage is applied.
 13. The electric-field distribution measurementmethod for a semiconductor device set forth in claim 8, beingcharacterized in that said irradiation apparatus comprises a near-fieldoptical system, and thereby irradiates said laser beam onto saidtwo-dimensional circuit so as to scan it two-dimensionally by way of thenear-field optical system.
 14. The electric-field distributionmeasurement apparatus for a semiconductor device set forth in claim 8,being characterized in that said laser apparatus generates a laser beamwith a wavelength which is absorbed by the material of saidsemiconductor device.